[Cronet] Add BUILD.gn for legacy ios/CrNet project.

BUG=527059

Review-Url: https://codereview.chromium.org/2200323003
Cr-Commit-Position: refs/heads/master@{#415312}

diff --git a/ios/net/BUILD.gn b/ios/net/BUILD.gn
index 65c9eac..fff941a9 100644
--- a/ios/net/BUILD.gn
+++ b/ios/net/BUILD.gn

@@ -4,11 +4,11 @@
 
 import("//ios/build/config.gni")
 import("//testing/test.gni")
+import("//url/features.gni")
 
 source_set("net") {
   deps = [
     "//base",
-    "//base:i18n",
     "//net",
     "//url:url_features",
   ]
@@ -55,6 +55,10 @@
     "url_scheme_util.h",
     "url_scheme_util.mm",
   ]
+
+  if (!use_platform_icu_alternatives) {
+    deps += [ "//base:i18n" ]
+  }
 }
 
 test("ios_net_unittests") {